The invention relates to a multilayer laid scrim for sheet-like or 3-dimensional high-strength components comprising a structure made of several layers of glass fibers, synthetic fibers, aramid fibers and/or carbon fibers.
Multilayer laid scrims are required for fiber composite components that distinguish themselves, in particular, by the fact that they have hardly any weight and, moreover, outstanding mechanical characteristics. Depending on the application area, this could involve simple UD scrims (unidirectional scrims), but also MD scrims (multiaxial scrims). The multiaxial scrims have the advantage vis-a-vis the unidirectional scrims that a strength, especially tensile strength, not only exists in the axial direction, but also crosswise to the axial direction. Long-fiber reinforced components are an important application area for scrims. The composition and structure of the scrim in interplay with the production technology and the matrix material that is used essentially determine the characteristics of the subsequent component in the form of a composite component. The special advantage here is the fact that there is a higher level of use of the specific characteristics of the above-mentioned fibers with a simultaneous reduction in the production costs and therefore the component costs.
Glass fibers, synthetic fibers, aramid fibers or carbon fibers that are arranged in the form of individual filaments next to one another are used to manufacture the UD scrims, and they are held together with an adhesive fiber mesh, for instance, before further processing is done. In addition, the possibility exists to hold the individual filaments in place in an improved way by sewing them.
Various techniques can be used to manufacture the multiaxial scrims. A well-known process provides for further UD scrims to be laid at an angle of 45 degrees, for example, onto a work table or a 0° position of a UD scrim in connection with this. To this end, a cutting-and-laying technique is used that supplies the UD scrims at an angle to the intended direction of transport and cuts the UD scrims to their specific length in the edge area. These processes are relatively complex and require a great deal of time, so cost-effective production is not possible.
For the above-mentioned reasons, a proposal is put forth below to put the UD scrims together by winding them around a plane to form a multiaxial scrim. At least two or more UD scrims are fed into a winding device for this purpose; the winding device can rotate around the longitudinal axis. Alternatively, the possibility exists to move the supply rolls of the UD scrims around a fixed winding table.
A process for manufacturing a multidirectional scrim web is disclosed in the published patent application DE 10 2005 000 115 A1, for instance; two further webs at an angle to the direction of extension are wound around a scrim whose fibers are aligned in the direction of extension of the scrim web in this process. The winding process leads to a multiaxial scrim that can be subsequently used as a multilayer laid scrim for sheet-like and 3-dimensional high-strength components. Carbon fibers can be used as a preference to manufacture the UD scrims, but the possibility also exists to manufacture UD scrims from glass fibers, aramid fibers or other synthetic fibers.